Datasheet

Lab Measurements
Equipment used:
Audio Precision
®
SYS-2722 signal source or equivalent
Voltage calibrator DVC-8500
Windows PC with two USB ports
Campbell (MAXREFDES4#) board
Nexys 3 development kit
12V DC power supply (for external power testing only)
Special care must be taken and the proper equipment must be used when testing the Campbell design. The
key to testing any high-accuracy design is to use sources and measurement equipment that are of higher
accuracy than the design under test. A low distortion signal source is absolutely required in order to duplicate
the results presented below. The input signal was generated using the Audio Precision SYS-2722. The FFTs
were created using the FFT control in SignalLab from Mitov Software.
AC and DC performance for on-board isolated power is shown in Figure 3 and Figure 4. AC and DC
performance for external power is shown in Figure 5 and Figure 6.
Figure 3. AC FFT using on-board isolated power, a 0.2V to 4.08V 1kHz sine wave input signal, high-impedance
input, a 20ksps sample rate, and a Blackman-Harris window.
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